Magnesium base alloy



Patented Nov. 12, 1940 UNITED STATES PATENT OFFICE land, Mi

ch., assignors to The Dow Chemical Company, Midland, Mich., a corporation of Michigan No Drawing. Application November 13, 1939, Serial No. 304,126

3 Claims.

The invention relates to magnesium base alloys. It more particularly concerns alloys of this nature having a high degree of formability coupled with other improved physical properties, such as 6 high tensile and yield strengths.

Magnesium alloys are being widely used in range of composition above indicated, we have found that in general a. preferred combination of properties, such as the most suitable ductility for forming operations, together with high tensile strength and greatly increased yield strength, is 5 obtained when the alloy contains from about 1 to 6 per cent of silver, 0.1 to 0.3 per cent of calcium, 1 to 3 per cent of manganese, and from 4 to 7 per cent of tin. v

The following table serves to illustrate the im- 1 proved properties of one of our preferred alloys over those of a related quaternary alloy. In the table, the per cent elongation is to be regarded as a measure of the ductility or iormability of the good formability permitting relatively sharp alloys. 15'

' Table messages? mag comm Yield Tensile Percent Yield Tensile Ag Ca Mn- Sn elongation strength stre in lbsfs q in. in lbsJsq. in.

bends to be made without the article developing external cracks have inferior characteristics as regards their tensile and yield strengths.

It .is' accordingly the principal object of the invention to provide a magnesium base alloy which can be made into rolled sheet or the like, possessing a sufllcient degree of ductility or formability at ordinary temperatures to be sharply bent, drawn, or otherwise shaped, while having greatly improved tensile and yield strengths.

Other objects and advantages of the invention will be apparent during the course of the following description.

Our invention resides in the discovery that a. magnesium base alloy composed of from 0.3 to 8 per cent of silver, 0.05 to 1 per cent of calcium, 0.1 to 3 per cent of manganese, and 0.1 to 8 per cent of tin, the balance being substantially all magnesium, is endowed with the aforementioned properties. While the properties of good formability or ductility coupled with increased tensile so and yield strengths are manifest over the entire which had been hot rolled at a temperature of from 500 to 700 F. to additional rolling in the 40 cold state, to bring about a total reduction in thickness of from 2 to 10 per cent. The properties selected for the table were those of the cold rolled specimens which showed the greatest tensile and yield strengths, while having at least a 1 per cent elongation in 2 inches. v

By comparison of the properties set forth in the above table it will beobserved that all of the properties of our new polynary alloy are superior so to those of the related quaternary alloy. For example, it will be noted that in the annealed state our new alloy possesses improved elongation as well as improved tensile and yield strengths over that of the related quaternary alloy. Also it will be noted that in the cold rolled state the yield and tensile strengths of the new alloy show a high degree of improvement over that of the related quaternary alloy. Similarly throughout the percentage range of alloying ingredients the properties of our new alloy show improvement over those of the related alloys.

While the new alloy is most useful in wrought form such as sheets due to its formability characteristics, it may also be used in making castings, iorgings, extruded forms, and the like. is further pointed out that the new alloy is amenable to solution and precipitation heat treatments, which accordingly modify its properties.

The new alloy may be compounded in any of the ways known in the art, such as by adding the alloying ingredients to molten magnesium under a suitable flux. The flux should be free from magnesium chloride if the calcium content of the alloy is to be above 0.3 per cent. In those instances where an alloy is to be compounded containing less than 0.3 per cent of calcium, magnesium chloride may be present in the flux without exerting a pronounced deleterious effect, but in this case it is usually desirable to add the calcium last and without too much stirring or agitation in order that the loss of calcium into the flux will be minimized or substantially prevented.

We claim:

1. A magnesium base alloy containing from 0.3 to 8 per cent of silver, 0.05 to l per cent of calcium, 0.1 to 3 per cent of manganese, and from 0.1 to 8 per cent of tin, the balance being magnesium.

2. A magnesium base alloy containing from 1 to 6 per cent of silver, 0.1 to 0.3 per cent or calcium, l to 3 per cent of manganese. and from 2 to 7 per cent of tin, the balance being magnesium.

3. A magnesium base alloy consisting of approximately 4 per cent of silver, 0.2 per cent of calcium, 2 per cent of manganese, and 5 per cent of tin, the balance being magnesium.

JOSEPH D. HANAWALT. JONH C. MCDONALD. 

